A survey released by Monmouth University, in New Jersey, on Monday found 50% of the state’s residents approve of Christie’s job performance and 44% disapprove — still a healthy amount of support at a time when few incumbents can boast majority backing. But that also represents a steep drop since the scandal, in which aides closed lanes leading to a busy bridge in an apparent political-payback ploy, first started to gain wider notice late last year. His approval rating was at 65% in December and 60% in January, down from a high-water mark of 70% shortly after he was inaugurated for a second term in early 2013. Among registered voters, only 49% approve of the job Christie is doing, the first time he’s dipped under 50% since 2011.

“This hole is getting deeper,” said Patrick Murray, director of the Monmouth University Polling Institute. “Christie’s image as the hero of [Hurricane] Sandy is now just a fading memory.”

Christie apologized and fired a top aide in January for the scandal, in which lane closures snarled traffic in a northern New Jersey town for days last year after the town’s mayor refused to back Christie’s re-election campaign. The Republican, seen as a leading 2016 presidential contender, has sought to project a business-as-usual aura even as his office deals with dueling investigations of the incident by state lawmakers and federal authorities. Christie stayed out of the public eye during the National Governors Association meeting last weekend in Washington, a time when state executives typically bask in national media attention.

The Monmouth poll of 803 New Jersey adults, taken from Feb. 19 to 23, has a margin of error of plus or minus 3.5 percentage points.